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The effects of Er3+ ion concentration on 2.0-μm emission performance in Ho3+/Tm3+ co-doped Na5Y9F32 single crystal under 800-nm excitation 下载免费PDF全文
Na5Y9F32 single crystals doped with ~0.8-mol% Ho3+,~1-mol% Tm3+,and various Er3+ ion concentrations were prepared by a modified Bridgman method.The effects of Er3+ion concentration on 2.0-μm emission excited by an800-nm laser diode were investigated with the help of their spectroscopic properties.The intensity of 2.0-μm emission reached to maximum when the Er3+ ion concentration was ~1 mol%.The energy transfer mechanisms between Er3+,Ho3+,and Tm3+ ions were identified from the change of the absorption spectra,the emission spectra,and the measured decay curves.The maximum 2.0-μm emission cross section of the Er3+/Ho3+/Tm3+tri-doped Na5Y9F32 single crystal reached 5.26 × 10-21 cm2.The gain cross section spectra were calculated according to the absorption and emission cross section spectra.The cross section for ~2.0-μm emission became a positive gain once the inversion level of population was reached 30%.The energy transfer efficiency was further increased by 11.81% through the incorporation of Er3+ ion into Ho3+/Tm3+ system estimated from the measured lifetimes of Ho3+/Tm3+-and Er3+/Ho3+/Tm3+-doped Na5Y9F32single crystals.The present results illustrated that the Er3+/Ho3+/Tm3+tri-doped Na5Y9F32 single crystals can be used as promising candidate for 2.0-μm laser. 相似文献
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用联吡啶在室温下催化(MA)与环氧丙烷(PO)、环氧氯丙烷(ECH)开环交替共聚,用核磁共振技术研究了共聚物的交替度,测得共聚物中马来酸酐含量达48%以上。 相似文献
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分别采用玻碳( GC)、铂( Pt)和金( Au)电极研究了在Br?nsted酸性离子液体[ HMIm] HSO4中电解水制氢的催化活性,活性大小为Pt > Au >> GC。水中离子液体的含量对析氢电流影响很大,当[ HMIm] HSO4含量为30%(V/V)时,Pt电极催化电解水产氢的阈值电位高达-0.3 V (Ag丝为准参比电极, Ag QRE),在-0.5 V (Ag QRE)处电流密度高达110.52 mA/cm2,为相同条件下Au电极的15倍,GC电极的650倍。计算结果表明,Pt电极在该电解液中的反应活化能为5.68 kJ/mol。电极的高催化活性与[ HMIm] HSO4电离产生的质子有关,使水以H3 O+的形式捕集电子,效率更高。 相似文献
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在DMSO/I2的氧化作用下,由2′,4′-二氢-6′-甲氧基-3′,5′-二甲基查耳酮可合成一种全新结构的黄酮:7-羟基-5-甲氧基-6,8-二甲基黄酮(产率91%),而在HCl/MeOH作用下则得到了两种黄烷酮:7-羟基-5-甲氧基-6,8-二甲基黄烷酮(产率70%)和5,7-二羟基-6,8-二甲基黄烷酮(产率20%)。 相似文献
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以5-甲基色胺盐酸盐和邻溴苯乙酸为例, 研究了5-甲基色胺衍生物的合成方法. 在室温下用二环己基碳二亚胺(DCC)作为脱水剂, N-羟基琥珀酰亚胺(NHS)活化酯法一锅法合成5-甲基色胺衍生物, 并通过FTIR、MS、1H NMR、13C NMR确定了目标化合物结构. 相似文献
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